U.S. Pat. No. 4,163,910 Matthews, et al, issued Aug. 7, 1979, is specifically incorporated in this disclosure by reference. The Matthews patent clearly discloses an MHD channel connected to the bottom of a steam generator of more or less conventional form. The invention in the incorporated disclosure relates to the recovery of heat for superheating fluids utilized by the MHD channel. The patent recognized a problem of directing the high velocity output gas of the MHD channel into the steam generator. A lower chamber was provided for the generator to reduce the velocity of the MHD output gas and to collect and remove slag. Thus, the connection between the MHD channel of the incorporated disclosure and the steam generator did not solve all of the problems related to coupling an MHD channel and a conventional generator.
The general function of the MHD channel is fairly well established in the prior art. Essentially, the MHD channel fuel and air are combusted into working fluid. At a sufficiently high temperature, the working fluid together with an ionizing seed, becomes a generating conductor which is passed through a static magnetic field at velocities which include supersonic speeds. The induced currents are collected by suitably placed electrodes from which direct current is connected to an external load. It is an object of all these combinations of MHD channels and steam generators to significantly increase the fuel conversion efficiency.
The high velocity gas output from the MHD diffuser is usually in a temperature range including 3800 F. It is necessary to provide a residence for the MHD channel gas during which the reducing conditions in the gas attenuate NO.sub.x. In addition to NO.sub.x attenuation, the channel gas temperature approach to the retrofitted utility steam generator must be compatible with the design temperature of the generator. At the same time, it is, of course, desirable to provide for the recovery of heat released by the temperature reduction of the gas between the MHD channel and the steam generator. Finally, the seed of the MHD channel must be recovered in a flow-train of stations in the steam generator.